Washington — The Bush administration is facing a long, hot summer of fierce litigation over who is, and who isn't, an enemy combatant in the war on terror.

Judges at the federal courthouse in Washington, D.C., are gearing up for an anticipated influx of habeas corpus petitions filed on behalf of terror suspects being held at the Guantánamo Bay, Cuba, prison camp.

The action was prompted by the US Supreme Court's June 12 ruling that foreign detainees at Guantánamo have the right to force the US government to prove the legality of their ongoing detention to a neutral judge. Many of the detainees have been held at Guantánamo for more than six years.

This is not how government lawyers had hoped to spend their summer and the remaining months of the Bush administration. The first military commission trial is scheduled to begin later this month at a specially-constructed judicial complex at Guantánamo Bay. Osama bin Laden's former driver, Salim Ahmed Hamdan, is set to stand trial.

But the Supreme Court's ruling is raising a string of questions not only about habeas proceedings in Washington, but also about whether the commission process itself must now comply with additional constitutional safeguards.

A military judge at Guantánamo has declined a request to postpone Mr. Hamdan's trial in light of the Supreme Court decision. But a federal judge in Washington is also set to examine the issue. In the meantime, the Defense Department is moving forward with the Hamdan case and others. On Monday, the Pentagon announced that military commission charges had been filed against Abd al-Rahim Al-Nashiri of Saudi Arabia for his alleged role in the October 2000 attack on the USS Cole. Mr. Nashiri became the 20th individual slated for a military commission trial at Guantánamo

The Bush administration has fought successfully for years to prevent the detainees at Guantánamo from gaining access to civilian judges and their higher standards of proof. They had argued that such efforts might trigger judicial chaos. Some critics of the Supreme Court decision are repeating that prediction.

Other legal analysts say the federal courts are more than up to the task. "Is there going to be a lot of hard work, sure there is," says Muneer Ahmad, a professor at American University's Washington College of Law. "But I don't think this is the kind of thing that is going to bring the courts to a grinding halt ... What is extraordinary is that it will have taken seven years for someone to actually get their case meaningfully heard [by a neutral judge]."

Habeas corpus petitions had been filed on behalf of more than 200 of the 270 detainees currently at Guantánamo. But those court challenges were put on hold in 2005 and, once again, in 2006 after Congress passed laws stripping the federal courts of the ability to hear habeas cases. Instead, the detainees were required to contest their status as enemy combatants through a less rigorous process involving so-called Combat Status Review Tribunals (CSRTs) – a hearing conducted by three military officers reviewing information presented by the government.

Now it will be up to federal judges in Washington rather than military officers in Guantánamo. Legal analysts say federal judges are likely to be skeptical of government assertions and more prone to demand evidence and answers.

That was the posture of a federal appeals court that criticized the government for relying on what it said was insufficient evidence to hold Huzaifa Parhat, an ethnic Uighur, for six years at Guantánamo. In a decision made public on Monday, the three-judge panel ruled that the government had failed to provide convincing evidence that Mr. Parhat was an enemy combatant.

The appeals court ordered the government to either release Parhat, transfer him from Guantánamo, or conduct a more probing CSRT hearing. The appeals court also invited Parhat's lawyer to file a habeas petition under the Supreme Court's recent ruling.

Combined with the Supreme Court's recent decision, the Parhat opinion marks the second major defeat this month for the Bush administration in its controversial approach to the war on terror. And it sets the stage for what some analysts say will be increasingly aggressive judicial oversight via newly filed habeas petitions.

Mr. Willett says that was the appeals court's approach. "The court said we are not going to roll over and rubber stamp this," he says. "You can't invoke the judicial branch of the United States without us acting like a court."

For lawyers working to ensure Guantánamo detainees receive fair treatment, the Supreme Court decision and the appeals court ruling represent the fruit of years of effort.

But Willett says he's not sure his client even knows of the victories. "I haven't told my client," he said. "We've asked for a phone call and the military has denied my request."